Dental Amalgam Separation and Recycling System

ABSTRACT

The present invention provides dental amalgam recycling systems, useful for recycling particles from a dental liquid effluent drawn, for example, from a suctioning device.

FIELD OF THE INVENTION

This invention relates to systems and apparatus suitable to removeparticles from effluent waste, and particularly, to remove amalgam andother metallic particles and other abrasive solids from dental officesuction effluent. The system also comprises a self contained recyclingcontainer to facilitate customer regulatory compliance and environmentalsafeguards.

BACKGROUND OF THE INVENTION

Dental amalgam is a dental filling material used to fill cavities causedby tooth decay. It has been used for more than 150 years in hundreds ofmillions of patients around the world.

Dental amalgam is a mixture of metals, consisting of liquid (elemental)mercury and a powdered alloy composed of silver, tin, and copper.Approximately 50% of dental amalgam is elemental mercury by weight. Thechemical properties of elemental mercury allow it to react with and bindtogether the silver/copper/tin alloy particles to form an amalgam. Seehttp://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/DentalProducts/DentalAmalgam/ucm171094.htm, accessed Sep. 9,2016.

Amalgam is used less often than in the past, mostly becausetooth-colored materials now can be used. However, the newer materialscan't be used for all dental situations, amalgam is less costly thannewer materials and it lasts longer, especially in teeth that undergo alot of pressure and wear from chewing.

Better dental health overall coupled with increased demand for moremodern alternatives such as resin composite fillings (which match thetooth color), as well as public concern about the mercury content ofdental amalgam, have resulted in a steady decline in dental amalgam usein developed countries, though overall amalgam use continues to riseworldwide. Stein, P S; Sullivan, J; Haubenreich, J E; Osborne, P B(2005). “Composite resin in medicine and dentistry”. Journal oflong-term effects of medical implants. 15 (6): 641-54.doi:10.1615/jlongtermeffmedimplants. v15.i6.70. PMID 16393132.

Although amalgams are less frequently used in developed countries fornew dental fillings than in the past, amalgams continue to make up aportion of the particle component of dental office effluent mainlybecause of the fact that old fillings made of amalgams are drilled outand removed in the effluent waste when new fillings are effected toreplace the old. Further, as noted above, even under current dentalpractice, an amalgam is preferred for some tooth filling situations.

Because mercury is a poison that can accumulate in living tissues andcan pose a health hazard to species in a food chain exposed tomercury-containing compounds, and since humans are inevitably at the endof the food chain, it follows that effluent containing amalgams can posea health hazard to the community at large. Also, certain metals such assilver are commercially valuable if recovered in quantity. For thosereasons, it is desirable to devise systems, apparatus and processes forremoving amalgams from dental office effluent and efficiently recyclingthose amalgams.

In addition to removing amalgams, other matter disposed into dentaloffice suction effluent includes aluminum oxides used in air abrasiontreatments and other solid waste material. These solid materials tend towear out or damage vacuum pumps and other equipment downstream of thedental chair suction apparatus, and also constitute effluent watercontaminants. Therefore, it is desirable for the apparatus to removesolid abrasive material and other particulate waste from the dentaloffice suction effluent.

The World Health Organization also points out that amalgam separators,installed in the waste water lines of many dental offices, dramaticallydecrease the release of mercury into the public sewer system. However,critics say that the separators are still not mandatory in some statesof the United States. “Purchasing, installing and operating dentalamalgam separators: Practical issues”. The Journal of the AmericanDental Association. 134 (8): 1054-65.doi:10.14219/jada.archive.2003.0319. PMID 12956345. Recently, the EPAhas enacted nation-wide regulations requiring amalgam separators indental offices.

Previously known apparatus for removing amalgam particles from dentaloffice suction effluent are known to include a collecting tank forcollecting a day's accumulation of suction effluent from one or moresources of such waste. The waste is sucked from the dental chair suctionapparatus and into the collecting tank by a vacuum pump. When the vacuumpump is turned off, an outlet valve is opened and the accumulated wasteis deposited into a separation device intended to separate metalparticles from the effluent liquid. Flow into the separation device isinduced by the head of fluid in the collecting tank. Particles passingthrough the separation device are separated from the waste by gravityand settle to the bottom of the separation device. The flow rate isdependent on the head inside the collecting tank; as the headdiminishes, the flow rate also diminishes. The changes in flow rate areundesirable because the particle separation rate is affected, and thesystem becomes prone to plugging when the flow rate decreases. Also,since the waste can be deposited only when the vacuum pump is off, wasteis usually moved to the separation device at the end of the day. As aresult, the collecting tank and separation device tend to be undesirablylarge and the whole process is time consuming.

Another known apparatus is a centrifuge type system that separatesheavier metal particles from effluent liquid by collecting the particlesat the peripheral wall of the centrifuge. This apparatus does noteffectively separate lighter particles, and is expensive to purchase andoperate due to the complexity of its mechanical parts.

Yet another known apparatus uses a dedicated mechanical pump to suctionwaste liquids through a separator device. Again, a dedicated pump can beexpensive to purchase and to maintain, and can be undesirablyspace-consuming.

Such known systems can become quite complex, unwieldy and expensive, asfor example that disclosed in U.S. Pat. No. 5,885,076 granted 23 Mar.1999. It teaches the use of sedimentation, co-precipitation andfiltration in an expensive complicated apparatus that is probablyeconomical, if at all, only for relatively large installations such as amilitary base dental complex.

U.S. Pat. No. 6,692,636 and U.S. Pat. No. 6,596,754 are patents thatdisclose systems for removing amalgam from dental office suctioneffluent.

After collecting the amalgam and other solid waste the dentist is leftwith the problem of what to do with the waste. Either the dentist has todeal with his own hazardous waste or he can send his collected materialto a recycler. In either case, the “collection container” needs to bedisposable and easily replaceable.

Existing recycling programs generally require the provision of bulkyshipping materials and the delivery of those materials to the dentistfor every full container. If such materials are not provided and thematerials are not properly recycled a large part of the benefit ofcollecting the amalgam waste can be lost. It is important that the wasteis recycled under federal guidelines in order to make sure the fullbenefits of amalgam separation are achieved.

Additionally, containers for collection, such as dental amalgamrecycling systems, can be compromised by incorrect installation ormisalignment, which can cause O-rings to deform and/or seal irregularly,and result in leakage.

SUMMARY OF THE INVENTION

The present invention overcomes many of the shortcomings of the priortechnology and achieves further advantages that will be apparent afterreviewing the following detailed description.

In one aspect, the invention comprises a dental amalgam recycling systemfor recycling particles from a dental liquid effluent drawn from asuctioning device. In certain embodiments, the dental amalgam recyclingsystem of the invention comprises:

(a) an air-water separator tank for receiving said effluent, saidair-water separator tank having an air-water separator tank inlet influid communication with said suctioning device, an air-water separatortank liquid effluent outlet and an air-water separator tank air outlet;

(b) a detachable recycling container, said recycling container actingprimarily under the influence of gravity to cause settlement of saidparticles; said recycling container having a recycling containereffluent inlet port connected to said air-water separator tank liquideffluent outlet and said recycling container further having an effluentoutlet port;

(c) wherein the air-water separator tank also includes an internalsuction conduit;

(d) wherein the recycling container comprises threads;

(e) wherein the recycling container effluent inlet port and therecycling container outlet port are not the same height.

In certain embodiments, the dental amalgam recycling system furthercomprises (f) a threaded shipping cap, wherein the threads of theshipping cap and the threads of the recycling container arecomplementary such that, when the shipping cap is fitted in place, theshipping cap forms a tight seal with said recycling container.

While in use, the dental amalgam recycling system is functionallyassociated with a vacuum pump having a vacuum pump inlet. The vacuumpump is typically a pre-existing part of the dental office facility. Inparticular embodiments, the dental amalgam recycling system isphysically connected with a vacuum pump via a suction conduit in theair-water separator. In certain preferred embodiments, the suctionconduit is an internal suction conduit within the air-water separator.

In certain embodiments, the dental amalgam recycling system of theinvention further comprise a first plug for said recycling containerinlet port and a second plug for said recycling container effluentoutlet port. Said first and second plugs may be held tightly in place bysaid threaded shipping cap when said shipping cap is fitted in place.

In certain embodiments, the dental amalgam recycling system of theinvention further comprise an O-ring that provides an air and effluenttight seal when said shipping cap is fitted in place.

In certain embodiments, the invention comprises a container, useful as adental amalgam recycling container, comprising threads for attachment ofa shipping cap. In certain embodiments, the dental amalgam recyclingcontainer further comprises two plugs held in place by said shipping capand an O-ring fitted in an O-ring groove to prevent leaks. The dentalamalgam recycling containers of the present invention may furthercomprise a two tier cap that enables people with hands of differentsizes to grip the cap and tighten to achieve a very tight seal.

In certain embodiments, the invention comprises an adapter for anair-water separator tank, wherein the adapter enables a recyclingcontainer without compatible effluent ports to attach to an air-waterseparator tank. Said air-water separator tank may comprise, for example,a component of a dental amalgam recycling system, as described above. Incertain embodiments, the adapter may comprise threads. In alternativeembodiments, the adaptor may be without threads.

As described above, the potential for leakage exists in a collectioncanister such as a recycling container used in the dental amalgamrecycling systems described herein. Such leakage may occur, for example,due to incorrect installation, or due to misalignment of a container andits intended mating partner, such as the air-water separation tank orits intended cap, such as a threaded shipping cap, which may causeO-rings to deform and/or seal irregularly. In order to address thisproblem and/or reduce the potential for leakage, a collection canister,such as a recycling container used in a dental amalgam recycling system,may have one or more irregular ‘keyways’ cast into its outside topmating surface, and the intended mating partner, such as the air-waterseparation tank, or the shipping cap, may have one or more corresponding‘key(s)’ be cast into its mating surface, such that the key(s) andkeyway(s) must be aligned in order for the collection canister (e.g.,the recycling container) and its mating partner (e.g., the air-waterseparation tank; or the shipping cap) to mate properly. This key/keywaysystem can help ensure even pressure across the entire circumference ofthe O-ring surface on each port. Similarly, such key(s) and keyway(s)may be used to ensure proper replacement of the container and/or theair-water separation tank, such that incorrect replacement can beavoided or minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of an embodiment of particle removaland recycling apparatus according to the invention, for particular usein a dental office.

FIG. 2 is a schematic side view of an embodiment of particle removal andrecycling apparatus according to the invention, for particular use in adental office.

FIG. 3 a is a schematic view of an embodiment of a universal adapter forfitting various different sized recycling containers to the air-waterseparator of the present invention.

FIG. 3 b is a schematic view of an alternative embodiment of a universaladapter for fitting various different sized recycling containers to theair-water separator of the present invention.

FIG. 4 a is a schematic view of an embodiment of a recycling containerand cap system of the invention.

FIG. 4 b is a schematic perspective depiction of an embodiment of arecycling container and cap system of the invention.

FIG. 5 a is a schematic inside view of an embodiment of a recycling capfor the recycling containers of the invention.

FIG. 5 b is a schematic depiction of a recycling cap according to theinvention fitting on a partial view of a recycling container accordingto the invention.

-   -   1—Backplate    -   2—Waste Inlet (from dental practice)    -   3—Air/water Separator Top    -   4—Top Support Bracket    -   5—Air/Water Separation Tank    -   6—Suction tube    -   7—Air/Water Separator Base    -   8—Outlet Tube (to vacuum system)    -   9—Recycling Container Top    -   10—Lower Support Bracket    -   11—Restrictor    -   12—Detachable Recycling Container    -   13—Retaining Pins (2)    -   14—air-water separator tank effluent outlet port    -   15—recycling container inlet port    -   16—recycling container outlet port    -   17—recycling container threads    -   18—two tier recycling cap    -   19—O-ring groove    -   20—cap plugs    -   21—O-ring

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

According to one aspect of the instant invention, an apparatus isprovided for removing and recycling metal-containing particles and otherwaste particles from effluent, particularly effluent from a dentaloffice. While herein the term “metal particles” may frequently beemployed, it is contemplated that the apparatus is capable of separatingother solid particles from effluent liquid.

According to one aspect of the invention, an apparatus for removingmetal particles and other solid particles from liquid suction effluentcan be installed in a dental office using a pre-existing suction/vacuumpump system. The apparatus may share a common vacuum pump withconventional dental chair suction apparatus, without interrupting theuse of suction equipment at the dental chairs.

Removal of solid particles from liquid suction effluent is effected bysedimentation.

In accordance with a one embodiment of the invention, the dental officesuction effluent is passed from dental chair suction equipment outletsto an air water separator tank via a suitable inlet port for the tank.The air-water separator tank in turn passes effluent into a sedimentarydeposit tank, closed on all sides when in use and preferably readilydetachable for emptying or replacement.

In certain aspects of the instant invention the sedimentary deposit tankhas a secondary function as a recycling container. In another aspect ofthe invention this recycling container can have features built in tomake recycling easier and to reduce the amount of packaging and waste inthe recycling system.

In another embodiment of the invention designed to minimize the spacerequired to install the amalgam recycling system the air-water suctiontube is internalized—within the air-water separator tank.

FIG. 1 and FIG. 2 shows two views of the separation apparatus accordingto the present invention in detail. Effluent from the dental chairs anda quantity of air are sucked through a suction apparatus exhaustconduit, through an air-water separator tank inlet 2, and thence into anair-water separator tank 5. The liquid effluent passes out of theair-water separator tank 5 via air-water separator tank outlet port 14,while air passes downstream via the air suction tube 6 while maintainingconstant vacuum upstream of amalgam separator.

The air-water separator tank effluent outlet port 14 passes effluent bygravity out of the air-water separator tank 5 and into the detachablerecycling container 12 through the recycling container inlet port 15 fortarget particle separation by sedimentation. Solids settle andaccumulate in the bottom of Recycle container 12. Liquid content ofwaste flows primarily by gravity, although intermittently assisted byvacuum through Restrictor 11 which slows the flow rate of liquid toassist in sedimentation process and ultimately “clean” effluentdischarge through the recycling container outlet port 16.

Outlet ports 16 and inlet port 15 can be a variety of shapes and sizes,square, oval (as depicted), round or even more unusual shapes like astar. Preferred ports are those that provide a tight seal, allow foreasy removal, and do not break. Oval or round are preferred embodiments.Round are most preferred.

A vacuum at the outlet tube 8 is generated when the vacuum pump isoperating, thereby sucking air out of the air-water separator tank 5 viasuction tube 6 while maintaining vacuum upstream of amalgam separatorapparatus. Effluent from the recycling container 12 passes through therestrictor 11 where remaining non-settable fine particles are removedfrom the effluent and into the recycling container outlet port 16 to bedischarged from the apparatus via common outlet tube 8. Matter sucked bythe vacuum pump, generally free of removed solids, is discharged viavacuum pump into a municipal drain of the public sewage system.

The system is provided with a simple back plate 1 for easy dental officeplacement as well as removable retaining pins 13 to ensure the recyclingcontainer does not detach from the air-water separation tank 5 whenthere is no vacuum in the system.

In certain embodiments, the recycling container ports 16 and 15 may bedifferent heights in order to aid in alignment of the detachablerecycling container 12 in the air-water separator base 7. In a preferredembodiment, the outlet port 16 engages before the inlet port 15 whileduring removal the inlet port 15 disengages first. This causes a smallvolume of fluid to be pulled out of the collection container back intoair-water separator tank 5 creating head space and eliminating upwardforce of vacuum which eases removal of recycle container 12 by operator.Existing devices require rocking, wiggling or applying extensive downforce for removal of recycle container 12.

In one preferred embodiment of the invention designed to minimizerecycling costs and waste, the recycling container/sedimentary deposittank has threads 17 built into the container to enable the addition of aliquid tight top for shipping.

FIG. 3 shows a schematic diagram of an adapter according to theinvention to enable the use of recycling containers from a variety ofsources that are lacking in correctly shaped ports 16 and 15 orotherwise are unable to fit the air-water separator tank 5 according tothe invention due to shape differences.

FIG. 4 a shows a schematic diagram of the recycling container and capsystem (see FIG. 5 for more cap 18 detail) according to the presentinvention. The cap 18 is a two tier shape to allow for a tight grip byboth a big and smaller hand in order to achieve a strong seal asrequired by the invention. An O-ring 21 is provided and fits into anO-ring groove on the recycling container 12. Plugs 20 are used toprovide a first leak proof seal for the recycling container 12. Theseplugs 20 are held in place by the cap 18 when the cap is threaded ontothe recycling container as depicted in FIG. 5 b.

Generally, under present practice, the dental staff will not be able toremove deposited sediment from the recycle container nor removeaccumulated particle residues from the restrictor unit themselves. Thus,it is desirable that such removal be done by a competent effluentresidue processing facility. Therefore, under present practice, it isexpected to be preferred that the recycling container with its enclosedrestrictor unit be removed when full, or periodically replaced by freshtanks from time to time as required. The spent tank with an accumulationof metallic and other particles can then be sent to a processingfacility for proper disposal of the targeted metallic particles, such asmercury, and recovery of precious metals such as silver.

Although the sedimentary deposit process is effective to remove asatisfactorily high proportion of the target particles desired to beremoved from the effluent, the recycling container desirably includes anoutlet restrictor right in the chamber to catch any floating materialsas well as any other materials that did not settle out.

If the recycle container is not changed as required or filled beyondnormal capacity, waste liquid from dental practice may back up into airwater separator tank. Should this occur, effluent overflows through theair suction tube and into the outlet port and is discharged into thevacuum pump draw line and thence eventually into the municipal drain.However, it is desirable that the system should operate in such a manneras to avoid having the air-water separator tank become completely full,since effluent exiting through the air outlet port will containparticles that will not be separated by the separator. If, however, sucha by-pass condition occurs at no time will the suction generated by thevacuum pump be lost or interrupted at the dental office.

In a further embodiment of the invention oriented towards large-scaleinstitutional applications, in which many dental chairs or other sourcesof effluent are connected to the same suction and drain services,several parallel-connected recycling containers and associatedapparatus, each such composite apparatus including a air-water separatortank and preferably one, or alternatively two attached recyclingcontainers, may be operated in parallel to provide sufficient treatmentcapacity for large effluent volumes.

All publications, web-sites, patents and patent applications cited inthe specification are hereby incorporated herein by reference in theirentirety for the disclosure for which they are cited.

Having read the above specification, other alternatives and variants ofthe above described methods and apparatus suitable for practicing themethods will occur to those skilled in the technology. Suchalternatives, modifications and variants fall within the scope of thepresent invention.

The invention as described above also includes the followingnon-limiting claims, which describe particular embodiments of theinvention.

1. A dental amalgam recycling system for recycling particles from adental liquid effluent drawn from a suctioning device, comprising: (a)an air-water separator tank for receiving said effluent, said air-waterseparator tank having an air-water separator tank inlet in fluidcommunication with said suctioning device; an air-water separator tankliquid effluent outlet; and an air-water separator tank air outlet; (b)a detachable recycling container, said recycling container actingprimarily under the influence of gravity to cause settlement of saidparticles; said recycling container having a recycling containereffluent inlet port connected to said air-water separator tank liquideffluent outlet; and said recycling container further having an effluentoutlet port; (c) wherein the air-water separator tank also includes aninternal suction conduit; (d) wherein the recycling container comprisesthreads; (e) wherein the recycling container effluent inlet port and therecycling container outlet port are not the same height.
 2. The dentalamalgam recycling system of claim 1, further comprising: (f) a threadedshipping cap for said recycling container; and
 3. The dental amalgamrecycling system according to claim 1, further comprising a first plugfor said recycling container inlet port and a second plug for saidrecycling container effluent outlet port.
 4. A dental amalgam recyclingsystem according to claim 3 wherein said first and second plugs are heldtightly in place by said threaded shipping cap when said shipping cap isfitted in place.
 5. A dental amalgam recycling system according to claim4 further comprising an O-ring that provides an air and effluent tightseal when said shipping cap is fitted in place.
 6. A dental amalgamrecycling container comprising threads for attachment of a shipping cap.7. A dental amalgam recycling container according to claim 6 furthercomprising two plugs held in place by said shipping cap and an O-ringfitted in an O-ring groove to prevent leaks.
 8. A dental amalgamrecycling container according to claim 7 further comprising a two tiercap that enables people with hands of different sizes to grip the capand tighten to achieve a very tight seal.
 9. An adapter for an air-waterseparator tank wherein the adapter enables a recycling container withoutcompatible effluent ports to attach to the air-water separator tank ofthe dental amalgam recycling system of claim
 1. 10. An adapter accordingto claim 9, wherein the adapter is without threads.
 11. A dental amalgamrecycling system according to claim 1, wherein said recycling containerfurther comprises one or more irregular keyways cast into its outsidetop mating surface; and said air-water separation tank has one or morekeys cast into its mating surface, such that the keys of the air-waterseparation tank and the keyways of said recycling container must bealigned in order for said recycling container and said air-waterseparation tank to mate securely.
 12. A dental amalgam recycling systemaccording to claim 2, wherein said recycling container further comprisesone or more irregular keyways cast into its outside top mating surface;and said threaded shipping cap has one or more keys cast into its matingsurface, such that the keys of said shipping cap and the keyways of saidrecycling container must be aligned in order for said recyclingcontainer and said shipping cap to mate securely.